This invention relates to improvements in the art of sliding gate valves. Sliding gate type throttling valves have been known for some time. However, their construction has been cumbersome and expensive in that the inner valve parts were contained between machined and flanged (separately cast) housing parts. The stationary plate member had to be sealed against at least one machined surface within said cast housing and further seals have to be implemented to prevent fluid from leaking out at the intersection between the two housing halves.
In contrast, the housing of my invention is made from tubular bar stock, eliminating the possibility of a porous casting. There are no internal seals, since the stationary plate member abuts and seals directly against the ordinary pipe line flange gasket, thereby eliminating at once the commonly feared possibility of leakage between valve seat (stationary plate) and the retaining housing. Furthermore, all internal valve parts are readily removable through one end of the tubular bar stock housing for ultimate ease of assembly and maintenance.
The absence of cast, separate retaining housing shells allows the design of a tubular bar stock body to fit snugly within the inner periphery of the circle of bolts connecting a pair of companion pipe line flanges, i.e. there is no longer need for separate valve housing flanges, thereby effecting great cost savings.
A further object of the invention is the ability to invert the movable plate 180.degree., in order to reverse the direction of opening or closing without need for additional parts or readjustment of valve stems.
Finally, in contrast to present state of the art devices, my invention completely eliminates all fasteners, such as nuts or pins connecting the valve stem with the sliding gate and which can corrode or dislodge during service and thereby pose a threat to reliable service of the valve.
These and other advantages of my invention will become apparent from a study of the following detailed description and drawings.